This is a planning grant for a multicenter, double-blind, randomized study of two different medical treatments to prevent recurrence of duodenal (DU) and gastric (GU) bleeding. The hypothesis to be tested is that eradication of Helicobacter pylori (H. pylori) infection will cure patients of their chronic peptic ulcer disease and eliminate the risk of recurrent ulcer hemorrhage. Approximately 170 patients with a clinically significant DU hemorrhage and 170 patients with GU hemorrhage will be enrolled in this study after ulcer healing and antral infection with H. pylori -are documented. Eligible patients will be randomized to receive either a one time course of antimicrobial therapy (Metronidazole 250 TID, tetracycline 500mg TID, and bismuth subcitrate 240mg BID for two weeks) and an histamine 2 receptor antagonist (H2RA) placebo maintenance for the entire duration of the study or antimicrobial therapy placebo for two weeks and full dose H2RA as maintenance for the entire duration of the study. Patients will have antacid tablets for prn treatment of ulcer symptoms and will be followed for a mean of 30 months. The specific aims are: 1) to determine the efficacy and safety of a one time course of antimicrobial therapy versus full dose H2RA in prevention of DU and GU rebleeding, 2) to assess the role of H. pylori in DU and GU recurrence and rebleeding, 3) to compare the effect of full dose H2RA versus antimicrobial therapy on the long-term rates of H. pylori eradication and 4) to compare the direct cost (unscheduled use of health care) and indirect costs of care (time lost from work or usual activity) for the two treatment groups. The primary outcome to be evaluated by treatment is the recurrence rate of bleeding DU or GU. Secondary outcomes are frequencies of symptomatic ulcer and treatment failure, and direct and indirect costs of care. Survival analysis will be used in addition to other statistical methods. This study is especially significant because 1) new scientific information about treating a major complication of peptic disease will result, 2) the efficacy, safety and cost of H. Pylori eradication for patients with an ulcer hemorrhage will be defined, and 3) these outcomes will have profound implications for the management of a large group of patients worldwide with peptic ulcer disease.